1. Prior Art
My invention relates to a clamping device or chuck for axially clamping a tool, especially a disk.
A clamping device for clamping a tool to a flange on a driven spindle is known comprising a clamping nut, which can be screwed on a threaded spindle portion of the spindle on its free end, and a clamping disk which is arranged axially between the tool and the clamping nut, is supported at the clamping nut and can press against the tool and press the latter against the flange. Such clamping devices are chiefly suitable for portable hand-held machine tools and particularly for grinding machines. A clamping device of the aforementioned type is known (DE-PS 30 12 836) in which the clamping disk consists of an element which is approximately hat-shaped in cross section and is supported axially against the flange of the clamping nut via a helical spring. In screwing on and tightening the clamping nut, this clamping disk is pressed axially against the tool via the axially compressed spring, and the tool is accordingly tightened against the flange on the spindle side. The front side of a cylindrical shoulder of the clamping nut comes into immediate contact at a facing axial side of the flange on the spindle side and, if the clamping nut is tightened further, the flange on the spindle side is tightened together with the clamping nut, possibly until the rear flange comes into contact axially at the shoulder surface of the spindle forming the supporting element. It is to be achieved by means of this, in an angle grinder, that the grinding disk is clamped with defined contact pressing pressure and that this contact pressing pressure is ensured. This clamping device is also supposed to make it possible to exchange the grinding disk quickly and simply and simultaneously to prevent an overloading of the hand-held machine tool, particularly the angle grinder. That is, if the torque acting on the grinding disk is too great, the grinding disk stops, while the rear flange and the clamping nut, with the clamping disk, execute a relative movement thereto. This clamping device counters the effect whereby the clamping nut continues to tighten by itself during operation, which would otherwise considerably impede the loosening of the clamping nut when changing the grinding disk. Nevertheless, it is only possible to loosen the clamping nut with the use of a special auxiliary tool, wherein the spindle must be held reciprocally by means of a second auxiliary tool, e.g. a wrench, depending on the design of the machine.